Current collecting apparatus

Abstract: A current collecting apparatus provided with sliders 2 for collecting electric power from a power feeder 1, a current collector 3 for holding the power, an insulator for insulating and supporting the current collector 3, and a flexible conductor for delivering the power held in the current collector 3 to a conductor 5, which is connected to the flexible conductor and used for supplying the power to the vehicle side. The conductor 5 and the insulator 4 are disposed so that the former is offset with respect to the latter in the crosswise direction of a railway vehicle. With this arrangement, aerodynamic noise emanating from the current collector loaded on the vehicle running at high speed can be substantially reduced.

Description: The present invention relates generally to current collecting apparatus for railway vehicles and more particularly to a current collecting apparatus fit for use in a vehicle on a high-speed railway. Railway vehicles using electric power as a power source are generally equipped with current collecting apparatus on their roofs for collecting electric power by contact with overhead power lines. Such a current collecting apparatus arranged as a vertically movable assembly is known from FR-A-2 664 214. Another current collecting apparatus for a railway vehicle is known from FR-A-2 657 052. This current collecting apparatus comprises a current collector for collecting electric power from a power feeder, which current collector has a shape of an inverted U. The current collector is supported on the vehicle by two insulators. Furthermore the current collecting apparatus according to FR-A-2 657 052 comprises two conductors for conducting the power received from the current collector, whereby one conductor is arranged immediately adjacent to one insulator and the other conductor is arranged immediately adjacent to the other insulator on the vehicle. Japanese Patent Laid-Open No. 304101/1992 discloses a noise reducing arrangement attainable by installing sound arresters (covers) in front and behind a current collecting apparatus as means for suppressing noise. This noise reducing arrangement is such that sound arresters are respectively installed in front and behind a current collecting apparatus to place the current collecting apparatus in the airflow decelerated thereby so as to prevent not only aerodynamic noise from being produced from the current collecting apparatus but also the aerodynamic noise from radiating therefrom. The prior art current collecting apparatus disclosed in the aforementioned Japanese patent publication is obviously intended to reduce the noise generated from the current collecting apparatus during relatively high-speed traveling. However, in the case of a high-speed railway in the next generation on which the operation is aimed at a speed of as high as 350 km/hr, there still arises a problem of aerodynamic noise originating from such noise arresters themselves and the measure taken to reduce noise by means of the current collecting apparatus can hardly be effective in high-velocity zones. Since the air resistance generated while vehicles are traveling increases in proportion to the square of the velocity, moreover, an increase in operating cost due to travel resistance originating from the sound arresters would pose a serious problem in the case of the Shinkansen in the next generation in which the commercial operation is aimed at a speed well over the present one, for example, as high as 350 km/hr. In view of the foregoing problems, an object of the present invention is to provide a current collecting apparatus so designed as to reduce not only noise but also air resistance springing therefrom on any high-speed railway in the next generation. According to the invention, this object is achieved by a current collecting apparatus for a railway vehicle, which apparatus comprises a current collector for collecting electric power from a power feeder, an insulator for insulating and supporting the current collector on the vehicle, and a conductor for conducting the power received from the current collector to a load, whereby the conductor and the insulator are disposed a predetermined distance apart in the crosswise direction of the vehicle. The aerodynamic noise is produced when disturbance in the air exists near the surface of an object. If, therefore, a conductor is placed on the downstream side of an insulator where such disturbance is stronger, fluctuations in pressure will be induced on the surface of the conductor and sound waves will be excited to cause resulting sounds to be radiated therefrom. According to the present invention, the conductor is located in a position on the downstream side of the insulator where the disturbance is weak instead of a position on the downstream side thereof where the disturbance is strong by shifting the conductor (hereinafter called "offset") so as to reduce the noise emitting from a current collecting apparatus. In a preferred embodiment of the current collecting apparatus according to the invention each of the insulator and the conductor has a central part in form of an extended shaft and a plurality of fins arranged at predetermined intervals, which fins are greater than the diameter of said central part, and the fins of at least either the insulator or the conductor are fitted to said central part thereof at a predetermined angle with respect to the axial direction of said central part. Preferably at least either the insulator or the conductor has a streamlined cross section in parallel to the floor face of the vehicle. Thereby a further noise reduction is achieved. In another preferred embodiment of the current collecting apparatus according to the invention an end portion of the conductor on the power feeder side has a curved surface. This also further reduces the noise of the current collecting apparatus. Preferred embodiments of the current collecting apparatus according to the invention are described with respect to the accompanying drawings in which Fig. 1 is an external appearance of a high-speed vehicle to which a current collecting apparatus embodying the present invention is applied. Fig. 2 is a perspective view of the current collecting apparatus of Fig. 1. Fig. 3 is an elevational view of the current collecting apparatus of Fig. 1. Fig. 4 is a side view of the current collecting apparatus of Fig. 1. Fig. 5 is a perspective view of another current collecting apparatus embodying the present invention. Fig. 6 is an elevational view of the current collecting apparatus of Fig. 5. Fig. 7 is a side view of the current collecting apparatus of Fig. 5. Fig. 8 is a bottom view showing the positional relation between the insulator 4 and the conductor 5 according to the present invention. Fig. 9 is a graphic representation showing the noise reduction effect of the current collecting apparatus according to the present invention resulting from wind-tunnel tests. Fig. 10 is a perspective view of still another current collecting apparatus embodying the present invention. Fig. 11 is an elevational view of the current collecting apparatus of Fig. 10. Fig. 12 is a side view of the current collecting apparatus of Fig. 10. Fig. 13 is a perspective view of still another current collecting apparatus embodying the present invention. Fig. 14 is an elevational view of the current collecting apparatus of Fig. 13. Fig. 15 is a side view of the current collecting apparatus of Fig. 13. Fig. 16 is a perspective view of still another current collecting apparatus embodying the present invention. Fig. 17 is an elevational view of the current collecting apparatus of Fig. 16. Fig. 18 is a side view of the current collecting apparatus of Fig. 16. Fig. 19 is a bottom view of the current collecting apparatus of Fig. 16. Fig. 20 is a sectional view of a flexible conductor showing still another current collecting apparatus embodying the present invention. Referring to Figs. 1 ∼ 20, embodiments of the present invention will be described. Fig. 1 is a partial perspective view of a railway vehicle which carries a current collecting apparatus embodying the present invention. Figs. 2, 3 and 4 are perspective, elevational and side views of a current collecting apparatus embodying the present invention with an insulator 4 and a conductor 5 which are supported with a pedestal 17. Further, Figs. 5, 6 and 7 are perspective, elevational and side views of another current collecting apparatus embodying the present invention with an insulator 4 and a conductor 5 which are supported with pedestals 17a, 17b, respectively. The current collecting apparatus is designed to supply electric power via a flexible conductor 11 and the conductor 5 to a vehicle 8, the power being fed from a power feeder 1 to a current collector 3 by contact therewith, and loaded on the vehicle 8 for which various measures have been taken to reduce noise. While no current is collected, the current collecting apparatus is housed in a housing dome 10 by turning a pivot mechanism 13 fitted to its lower part. In Figs. 1, 2, 4, 5 and 7, an arrow 15 denotes the direction in which the vehicle runs. The conductor 5 of this current collecting apparatus is placed a predetermined distance apart from the insulator 4 for insulating and supporting the current collector 3 in the crosswise direction of the vehicle (offset arrangement). Generally, aerodynamic noise is produced when disturbance in the air exists near the surface of an object. If, therefore, the conductor 5 is placed on the downstream side of the insulator 4 where such disturbance is stronger, fluctuations in pressure will be induced on the surface of the conductor 5 and sound waves will be excited to cause resulting sounds to be radiated therefrom. In order to avoid this phenomenon, the conductor 5 is located in a position instead of what is on the downstream side of the insulator 4 where the disturbance is strong by offsetting the conductor to reduce the noise emitting from the current collecting apparatus. The current collecting apparatus shown in Figs. 5, 6 and 7 is provided with the insulator 4 for supporting the current collector 3, the pedestals 17a, 17b and pivot mechanisms 13a, 13b right under conductive cable heads for supplying the electric power collected from the power feeder 1 to the vehicle 8. The dynamic lift occurs to the current collector 3 when the vehicle 8 rushes in and out a tunnel and passes by another can be taken by the pivot mechanism 13a installed right under the insulator 4 supporting the current collector. Therefore, no moment centering on the pivot mechanism 13a is produced notwithstanding the dynamic lift fluctuations occurring to the current collector 3. The pivot mechanism 13a thus contributes to the stability of the current collecting apparatus itself. Moreover, the provision of the pivot mechanism 13b right under the conductor 5 minimizes the displacement of a cable 12 coupled to the vehicle 8 from the lower end of the conductor 5 when the current collecting apparatus is accommodated in the housing cover while no electric power is supplied, thus decreasing metal fatigue due to the repetition of displacement. In consequence, the replacement period of the cable 12 can be made longer. Fig. 8 is a bottom plan view of the current collecting apparatus as an embodiment of the present invention. In this case, the distance H between the center of the insulator 4 and that of the conductor 5 in the longitudinal direction of the vehicle is set at 420 mm and the distance W therebetween in the crosswise direction thereof is set at 500 mm. In other words, W = 500 mm represents the offset quantity. The noise reduction effect is unachievable unless the offset quantity W is substantially great. As shown in Fig. 8, the conductor 5 is so positioned as to be covered with the current collector 3, whereby fine metal powder resulting from arcs as well as the friction between the power feeder 1 and sliders 2 is prevented from flying in all directions and sticking to the surface of the conductor 5. Breakdown is thus prevented from arising on the surface of the conductor 5, which contributes to improving insulation reliability. Further, it is desirable to connect the conductor 5 to the current collector 3 by the shortest route as shown in the Fig. 17, from the point of view of the aerodynamics noise reduction. Fig. 9 shows the relation between relative sound power levels (dB) and frequencies based on the estimated actual noises resulting from wind-tunnel tests as what is illustrative of noises emanated from the conventional current collecting apparatus of a lower-frame crossing type that has been employed in the existing Shinkansen vehicles "Nozomi" and the current collecting apparatus according to the present invention in which two of the cylindrical insulator 4 and the offset conductor 5 are installed right under the triangular current collector 3. White diamond-shaped symbols in Fig. 9 represent the test results of the conventional current collecting apparatus, whereas white triangular symbols denote those of the current collecting apparatus according to the present invention. The overall (OA) relative sound pressure level of the current collecting apparatus according to the present invention is made lower by about 19 decibels (dB) than that of the conventional current collecting apparatus with the effect of greatly improving noise reduction. Figs. 10 through 15 inclusive, show still another embodiment of the present invention. Figs. 10, 11 and 12 are perspective, elevational and side views of a current collecting apparatus having a common pedestal 17 for supporting an insulator 4 and a conductor 5, whereas Figs. 13, 14 and 15 are perspective, elevational and a side view of the current collecting apparatus having pedestals 17a, 17b for respectively supporting the insulator 4 and the conductor 5. In this embodiment of the present invention, the cross sections of the insulator 4 and the conductor 5 in parallel to the floor face of the vehicle are streamlined. With the streamlined cross sections of the insulator 4 and the conductor 5 thus arranged, the airflow becomes smoother than what passes by the conventional cylindrical insulator 4 and the conductor 5, accordingly making aerodynamic noise difficult to develop. As a result, a lower-noise current collecting apparatus can be built up. When the insulator 4 thus configured is employed, the advantage with respect to an edge face length, that is, the sum total of the length of an external line on one side of the axial cross section of the insulator 4 as one of the factors essential to the insulator 4 is as in the following. In the case of the conventional cylindrical insulator 4, a low-pressure plane is generated on the downstream side of the insulator 4 when the vehicle runs at high speed. In order to avoid the breakdown caused by a pressure drop, the edge face distance has heretofore been overestimated to counterbalance the pressure drop. However, some equipment conditions surrounding the insulator 4 may not permit any increase in the dimensions of the insulator 4 even when it is attempted to increase the edge face distance. In such a case, the appearance of any site where static pressure is extremely low on the downstream side of the insulator 4 can be avoided by streamlining the insulator 4 and this not only prevents the breakdown due to the voltage drop but also minimizes an increase in the edge face distance. By applying the configuration above to the conductor 5, similar effects will be anticipated. Figs. 16 through 19 inclusive, show still another embodiment of the present invention. Figs. 16, 17, 18 and 19 are perspective, elevational and side views of a current collecting apparatus having a streamlined smooth joint 16 between a current collector 3 and an insulator 4, and a bottom view of a current collector 3 as viewed from a vehicle 8 toward a power feeder 1. The cross sections of the insulator 4 and a conductor 5 are similar to those shown in Figs. 10 through 15. The streamlined joint 16 between the current collector 3 and the insulator 4 is intended to obviate an acute angle. If the current collector 3 and the insulator 4 are joined at an acute angle, a secondary airflow will be generated and may thus increase travel resistance. When an airflow near the wall surface sharply changes, moreover, aerodynamic noise may readily be produced as the airflow change accompanies pressure fluctuations. As the joint 16 between the current collector 3 and the insulator 4 is streamlined, a back flow arising on the downstream side of the insulator 4 can be reduced further in comparison with the case of the cylindrical insulator 4, which contributes to reducing the dynamic lift caused by the velocity differential of the air current decelerated by the insulator 4 to the current collector 3 from the vehicle side toward the power feeder 1. As shown in Fig. 17, moreover, the space between one end of the conductor 5 on the power feeder side 1 and the current collector 3 is set greater than the length of the joint 16 between the current collector 3 and the insulator 4. Since the conductor 5 is not placed on the downstream side of the insulator 4, the airflow near the conductor 5 brings about laterally unbalanced dynamic lift fluctuations, which may result in occurring pitching moment to the current collector 3. In order to steer clear of this problem, the conductor 5 is spaced a predetermined distance apart from the current collector 3 so as to retrain the generation of the pitching moment of the current collector 3 sprinting from the disturbance of the airflow on the downstream side of the current collector 3. The improvement of stable current collecting performance is thus planned. Fig. 20 shows still another current collector embodying the present invention. A cross section (a section taken on line C - C of Fig. 17) perpendicular to the longitudinal direction of a flexible conductor 11 extending from a current collector 3 to a conductor 5 is streamlined. As the flexible conductor 11 is thinner than the other component members of the current collector 3, the airflow on the downstream side of the flexible conductor 11 is considered what develops into a strong secondary dimensional airflow. Therefore, a Karman vortex which is likely to become an aerodynamic noise source is prevented from arising on the downstream side of the flexible conductor 11 by streamlining the cross section perpendicular to the longitudinal direction of the flexible conductor 11 so as to promote noise suppression. Also, just one slider 2 may be used depending on the situation.

Claims: A current collecting apparatus for a railway vehicle (8), which apparatus comprises a current collector (3) for collecting electric power from a power feeder (1), an insulator (4) for insulating and supporting the current collector (3) on the vehicle (8), and a conductor (5) for conducting the power received from the current collector (3) to a load, characterized in that the conductor (5) and the insulator (4) are disposed a predetermined distance (W) apart in the crosswise direction of the vehicle (8). The current collecting apparatus according to claim 1, characterized in that each of the insulator (4) and the conductor (5) has a central part in form of an extended shaft and a plurality of fins (4a) arranged at predetermined intervals, which fins (4a) are greater than the diameter of said central part, and the fins (4a) of at least either the insulator (4) or the conductor (5) are fitted to said central part thereof at a predetermined angle with respect to the axial direction of said central part. The current collecting apparatus according to any of the preceding claims, characterized in that at least either the insulator (4) or the conductor (5) has a streamlined cross section in parallel to the floor face of the vehicle (8). The current collecting apparatus according to claim 1 or claim 2, characterized in that an end portion of the conductor (5) on the power feeder side has a curved surface.

Inventors: HAGIWARA SYUYA, HATTORI MORISHIGE, IIDA AKIYOSHI, IKEGAWA MASAHIRO, KOBAYASHI KENJI HYAKUTARYO, TAKANO YASUSHI, HAGIWARA, SYUYA, HATTORI, MORISHIGE, IIDA, AKIYOSHI, IKEGAWA, MASAHIRO, KOBAYASHI, KENJI, HYAKUTARYO, TAKANO, YASUSHI
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1994
Main classification: B60L5
IPC codes: B60L5, B61D49, G10K11